The general problem with which we are concerned is elucidation of mechanisms of gene regulation which relate to the neoplastic process in humans. The phenomenon of ectopic protein synthesis in human cancer offers a good experimental model for investigating this problem. The ectopic synthesis of placental proteins by non-trophoblastic neoplasms is of special interest because of the frequent association of similar characteristics in neoplastic cells and embryonic cells. This has suggested a possible similarity between the mechanisms associated with the derepression of the genes synthesizing embryonic proteins and those involved in neoplastic transformation. Our investigation will make use of material obtained from clinical studies of patients manifesting evidence of ectopic synthesis of human chorionic gonadotrophin, human chorionic somatomammotrophin and placental alkaline phosphatase. We plan to initiate experiments in two fundamental categories. (1) Proof of ectopia: These experiments are designed to test the assumption that the placental proteins are indeed synthesized by non-trophoblastic tumors and the assumption that they are coded for by the same genes as their normal counterparts. Immunohistochemical studies of tumor will be used for cytolocalization of the placental proteins. Chemical structure of the ectopic and placental proteins will be compared by several methods to determine whether they are the same. (2) Studies on the regulation of gene expression in normal and neoplastic cells: we plan to measure and compare patterns of synthesis of placental proteins in normal trophoblast, in choriocarcinoma and in non-trophoblastic tumors to determine whether similar regulatory mechanisms are operant. Initially, these experiments will be performed in short term tissue slice cultures from normal trophoblasts and from tumors which synthesize placental proteins ectopically. We plan to develop cell lines of these two tissues and to use these together with cell lines of choriocarcinoma which are already available, to extend these experiments as well as to do cell hybridization.